The present invention relates to a color-balance control method of a multicolor image-forming apparatus such as a copying machine for color electronic photograph, a printer, etc.
In the multicolor image-forming apparatus for forming a multicolor image, i.e., a full color image such as a copying machine for electronic photograph, a printer, etc., it is necessary to stabilize the balance of the image having three colors, yellow, magenta and cyan for example, and balance these colors. In the conventional image-stabilizing method, a potentiometer for measuring the surface potential of a photosensitive element is disposed and the surface potential is made constant in accordance with the necessity to stabilize the image. In another conventional image-stabilizing method, a toner is adhered to a surface of the photosensitive element or a section for detecting the developing ability by a developing machine, and a light is irradiated onto a toner layer, and the reflected light is detected and the toner density is controlled such that the developing ability becomes constant.
In such conventional methods, the stabilizations of an latent image of the photosensitive element and the developing ability are separately performed so that a shift in balance of the colors is caused in the formation of the multicolor image, thereby unbalancing the gray color.
Further, in the conventional methods, since both the surface potentiometer of the photosensitive element and a photoelectric detector are used, the entire apparatus is complicated and the cost thereof is thereby expensive. Further, since both the potentiometer and the photoelectric detector are arranged near the developing machine, the apparatus tends to be dirty and the error in operation tends to be often caused. In particular, the conventional method for controlling the image density by controlling the toner density by the detection of a photoelectric sensor sometimes causes a mechanical abnormality in which the toner is scattered and accumulated in the shape of a film and the sensor is operated in error, etc., and an image abnormality in which a base material for forming the image thereon is dirty and the trace of a carrier is left by the toner and the toner is adhered to the carrier, etc.